Isotopes of francium with 126 or fewer neutrons have been looked for in bombardments of Th{sup 232} with 350 Mev protons from the 184-inch cyclotron. Fr{sup 212} with an apparent half-life of 19.3 minutes for branching decay by alpha emission (44%) to At{sup 208} and by orbital electron capture (56%) to Em{sup 212} has been found. Em{sup 212} is shown to be a 23-minute alpha-emitter. At{sup 208} decays primarily (99.5%) by orbital electron capture to Po{sup 208}, but shows 0.5% alpha-branching. The francium and emanation isotopes have alpha half-lives completely out of line with the predictions based on the previously known isotopes of these elements. Their high alpha stability is believed to be due to a closed shell of 126 neutrons in analogy to the behavior of elements 83-85. The non-existence of long-lived francium in nature is discussed in the terms of this and other recent work on francium isotopes.

Fireman(1) has reported the results of a rather difficult beta-particle coincidence counting experiment in which the decay of Sn{sup 124} by the simultaneous emission of two negative beta-particles, with a half-life between 0.4 x 10{sup 16} years and 0.9 x 10{sup 16} years, seems to have been observed. This note reports the results obtained from a different and somewhat simpler method of looking for the phenomenon of simultaneous emission of two beta-particles. These results are negative so far and show that this process is considerably less probable in the case chosen by us than in that reported by Fireman. The method consists of looking in uranium samples for 90-year Pu{sup 238} which would come from U{sup 238} by the double beta-particle mechanism since Np{sup 238} is heavier than U{sup 238}, which in turn is substantially heavier than Pu{sup 238}, in the isobaric triplet {sub 92}U{sup 238}-{sub 93}Np{sup 238}-{sub 94}Pu{sup 238}. This chemical method of investigation is particularly applicable to this isobaric triplet because there appears to be no other mechanisms to account for the Pu{sup 238} should it be found. The energetics of the situation are summarized in the following diagram, where the disintegration energies are derived from sources which …

The following report describes the developmental process of the determination of free nitric acid in solutions containing uranyl nitrate, aluminum nitrate and sodium dichromate.

This report discusses methods of producing aluminum nitrate for the Redox process. Large amounts of aluminum nitrate are consumed during the Redox process, so this report explores preparation of this material through the dissolution of hydrated aluminum oxide in nitric acid.

Report discussing experiments and developments in purification of graphite starting from March, 1949.

From abstract: "The present report describes experimental work performed to establish a procedure for the production of uranium metal wire. In all cases, the size of the initial rod was 1/2 inch diameter. Three materials were used: hot extruded tuballoy rod, high purity cast tuballoy rod, and cast U-235 rod."

Note presenting experimental investigations of boundary-layer suction through slots as a means of increasing the extent of laminar flow on airfoil sections. The results show that, with the use of suitable slots, substantial increases in the extent of laminar flow can be achieved by boundary-layer control with only a small expenditure of power. Results regarding slot geometry and arrangement, suction slots in an unfavorable pressure gradient, suction slots in a favorable pressure gradient, and determinations of the relations controlling the distribution of suction slots are provided.

This progress report discusses the activities of the P Division for the month of September, 1949. The B and F piles operated at 275 megawatts (MW) and the D pile at 305 MW throughout the month except for cutages listed under Area Activities. A total of 60.22 tons of metal, at an average concentration of 396 megawatt days/ton (MWD/ton) was discharged from the piles during the month. The 105-H Building was accepted from the Construction Division on September 28 with certain exceptions noted under the Operating Experience section of this report. At month end P Division operating personnel are making preparations for activation of the H pile. On September 28 the operation of the 300 Area oxide burning process was reduced from a two shift to a one shift five day operation. This change in schedule was possible as a result of working off the backlog of uranium oxide. The shipment of 200 tons of canned slugs to Building 105-DR for storage was completed on September 9 and the shipment of 250 tons of canned slugs to Building 105-H for the initial loading charge was completed on September 26.

This report describes the basic design, intermediate and final stacking procedures, and graphite behavior of nuclear reactors DR and H during construction. Included in the report are test records to substantiate basic design assumptions and data and the actual performance of the graphite during preliminary and final stacking.

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Report presenting an investigation of the two-dimensional aerodynamic characteristics of 15 NACA airfoils at four Reynolds numbers. The results indicate that the drag coefficient at the design lift coefficient and the maximum lift coefficient are the most important aerodynamic characteristics and are most affected by Reynolds number changes.

Report presenting an analysis of two matrix methods for calculating responses of linear systems for given forcing functions and indicial responses in order to find a method suitable for solving the inverse problem of calculating forcing functions from known responses. The results of both methods are compared with exact solutions for both the direct and the inverse problems.

From Summary: "The theory of plastic buckling, originally derived for individual plates, has been extended to apply to combinations of plates such as H- and Z-sections. The theory has been applied specifically to extruded H-sections of 75S-T6 aluminum alloy; the calculated buckling stresses agree satisfactorily with the stresses obtained experimentally."

Report presenting an experimental investigation of boundary-layer suction through slots as a means of increasing the extent of laminar flow on airfoil sections. Results regarding slot geometry and arrangement, suction slots in an unfavorable pressure gradients, suction slots in a favorable pressure gradient, and a determination of the relations controlling the distribution of suction slots are provided.

"A theoretical solution is given for the critical shear stress of a simply supported curved rectangular plate stiffened by a central stiffener offering no torsional restraint which lies in either the axial or circumferential direction. Results are obtained by means of the Galerkin method and are presented in the form of computed curves and tables" (p. 1).

From Summary: "The spanwise lift distributions of wings of low aspect ratio but of arbitrary plan form and angle-of-attack distribution have been analyzed by two well-established concepts: the virtual-mass concept and the Weissinger method. Both concepts have been found to yield the same simple integral expression for the spanwise lift distribution in terms of the spanwise angle-of-attack distribution. Tables and figures of lit distributions of low-aspect-ratio wings have been presented."

Report presenting information for the determination of the theoretical lift, damping-in-roll, and center-of-pressure characteristics for a group of plan forms at supersonic speeds. The information is presented in three forms: equations, figures presenting generalized curves, and figures presenting curves for representative groups of configurations. Several observations are made in regards to the effect of taper ratio, angle of sweep, and aspect ratio on the values of the derivatives.

Report presenting a strain-energy theory established for the calculation of the buckling load in pure bending of reinforced monocoque cylinders which have a symmetric cutout on the compression side and buckle according to general-instability patterns. The difference between this theory and other theories is the use of the axial wave length as an additional parameter whose value was determined from a minimum condition.

Note presenting the compressive buckling stress of outstanding flanges reinforced by bulbs, which was computed by the strain-energy method for flanges with 10 shapes and a range of lengths. The results were checked for some cases by computations based on a differential-equation method. The results were analyzed to determine which shape of flange gave the greatest support to the structure to which it was attached.

Report presenting an investigation of a model of the Kingfisher XAUM-2 flying torpedo to determine the pressure recoveries within the jet engine nacelle and to determine the effects of several changes in model configuration on the aerodynamic characteristics of the model. The effectiveness of elevons and tabs as control devices was also investigated.

Report presenting airspeed and altitude data for nonscheduled cargo operations of a Douglas DC-4 airplane between Seattle, Washington and Alaska during February and March of 1947 to determine the probability of reaching or exceeding given values of airspeed and Mach number. The total probability of exceeding a placard never-exceed speed of 266 mph depends primarily on exceeding the speed in descent. The probability was found to be about once in 100 hours of descent or once in 1000 hours of general flying time.